High performance same fiber composite hybrids by varying resin content only

ABSTRACT

Multi-panel ballistic resistant articles formed from woven and/or non-woven fibrous panels, each panel including varying quantities of a polymeric composition based on the total weight of the fibers and the polymeric composition. The hybrid structures provide excellent ballistic penetration resistance while maintaining a low weight. The ballistic resistant articles may be strategically positioned to dial in different levels of desired ballistic resistance for various applications.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of co-pending application Ser. No.12/565,071 filed Sep. 23, 2009, which is a division of Ser. No.11/527,924 filed Sep. 26, 2006, now U.S. Pat. No. 7,622,405, the entiredisclosure of which is incorporated by reference herein.

BACKGROUND

1. Field of the Disclosure

This invention relates to multi-panel ballistic resistant articlesformed from woven and/or non-woven fibrous panels, each panel includesvarying quantities of a polymeric composition coating based on the totalweight of the fibers and the polymeric composition.

2. Description of the Related Art

Ballistic resistant articles containing high strength fibers that haveexcellent properties against projectiles are well known. Articles suchas bullet resistant vests, helmets, vehicle panels and structuralmembers of military equipment are typically made from fabrics comprisinghigh strength fibers. High strength fibers conventionally used includepolyethylene fibers, aramid fibers such as poly(phenylenediamineterephthalamide), graphite fibers, nylon fibers, glass fibers and thelike. For many applications, such as vests or parts of vests, the fibersmay be used in a woven or knitted fabric. For other applications, thefibers may be encapsulated or embedded in a polymeric matrix material toform non-woven rigid, semi-rigid or flexible fabrics.

Various ballistic resistant constructions are known that are useful forthe formation of hard or soft armor articles such as helmets, panels andvests. For example, U.S. Pat. Nos. 4,403,012, 4,457,985, 4,613,535,4,623,574, 4,650,710, 4,737,402, 4,748,064, 5,552,208, 5,587,230,6,642,159, 6,841,492, 6,846,758, all of which are incorporated herein byreference, describe ballistic resistant composites which include highstrength fibers made from materials such as extended chain ultra-highmolecular weight polyethylene. These composites display varying degreesof resistance to penetration by high speed impact from projectiles suchas bullets, shells, shrapnel and the like.

For example, U.S. Pat. Nos. 4,623,574 and 4,748,064 disclose simplecomposite structures comprising high strength fibers embedded in anelastomeric matrix. U.S. Pat. No. 4,650,710 discloses a flexible articleof manufacture comprising a plurality of flexible layers comprised ofhigh strength, extended chain polyolefin (ECP) fibers. The fibers of thenetwork are coated with a low modulus elastomeric material. U.S. Pat.Nos. 5,552,208 and 5,587,230 disclose an article and method for makingan article comprising at least one network of high strength fibers and amatrix composition that includes a vinyl ester and diallyl phthalate.U.S. Pat. No. 6,642,159 discloses an impact resistant rigid compositehaving a plurality of fibrous layers which comprise a network offilaments disposed in a matrix, with elastomeric layers there between.The composite is bonded to a hard plate to increase protection againstarmor piercing projectiles.

Hybrid ballistic resistant structures, in and of themselves, are known.For example, U.S. Pat. Nos. 5,179,244 and 5,180,880 teach soft or hardbody armor utilizing a plurality of plies made from dissimilar ballisticmaterials, joining aramid and non-aramid fiber plies into a combinedstructure and utilizing polymeric matrix materials that deteriorate whenexposed to liquids. U.S. Pat. No. 5,926,842 also describes hybridizedballistic resistant structures utilizing polymeric matrix materials thatdeteriorate when exposed to liquids. Further, U.S. Pat. No. 6,119,575teaches a hybrid structure containing a first section of aromaticfibers, a second section of a woven plastic and a third section ofpolyolefin fibers.

The present invention provides new hybrid structures that provideexcellent ballistic penetration resistance while maintaining a lowweight. Particularly, the invention provides articles wherein ballisticperformance and article weight may be customized by manipulating thecontent of a polymeric matrix composition coating the fiber layerswithin an armor construction. The inventive construction allows theballistic articles to be strategically positioned to dial in differentlevels of desired ballistic resistance for varying applications.

SUMMARY

The invention provides a ballistic resistant material comprising, inorder:

a) a first panel comprising a plurality of fibrous layers, saidplurality of fibrous layers being consolidated; each of the fibrouslayers comprising a plurality of fibers, said fibers having a tenacityof about 7 g/denier or more and a tensile modulus of about 150 g/denieror more; each of said fibers having a surface, and the surfaces of saidfibers being coated with a polymeric composition; andb) a second panel attached to the first panel, which second panel isdifferent than the first panel, and which second panel comprises aplurality of fibrous layers, said plurality of fibrous layers beingconsolidated; each of the fibrous layers comprising a plurality offibers, said fibers having a tenacity of about 7 g/denier or more and atensile modulus of about 150 g/denier or more; each of said fibershaving a surface, and the surfaces of said fibers being coated with apolymeric composition; andc) said first panel containing a greater percentage by weight of thepolymeric composition in the first panel, based on the total weight ofthe first panel, than a percentage by weight of the polymericcomposition in said second panel, based on the total weight of thesecond panel.

The invention also provides a method of forming a ballistic resistantmaterial which comprises a series of ballistic resistant panels, themethod comprising:

a) providing a first panel comprising a plurality of fibrous layers,said plurality of fibrous layers being consolidated; each of the fibrouslayers comprising a plurality of fibers, said fibers having a tenacityof about 7 g/denier or more and a tensile modulus of about 150 g/denieror more; each of said fibers having a surface, and the surfaces of saidfibers being coated with a polymeric composition; andb) attaching at least one additional ballistic resistant panel, whereinat least one additional ballistic resistant panel is different from thefirst panel, to said first panel to thereby form a series ofinterconnected ballistic resistant panels; the at least one additionalpanel comprising a plurality of fibrous layers, said plurality offibrous layers being consolidated; each of the fibrous layers comprisinga plurality of fibers, said fibers having a tenacity of about 7 g/denieror more and a tensile modulus of about 150 g/denier or more; each ofsaid fibers having a surface, and the surfaces of said fibers beingcoated with a polymeric composition; said first panel containing agreater percentage by weight of the polymeric composition in the firstpanel, based on the total weight of the first panel, than a percentageby weight of the polymeric composition in at least one additionalballistic resistant panel, based on the total weight of the at least oneadditional ballistic resistant panel.

The invention further provides a ballistic resistant article formed froma ballistic resistant material, the ballistic resistant materialcomprising:

a) a first panel comprising a plurality of fibrous layers, saidplurality of fibrous layers being consolidated; each of the fibrouslayers comprising a plurality of fibers, said fibers having a tenacityof about 7 g/denier or more and a tensile modulus of about 150 g/denieror more; each of said fibers having a surface, and the surfaces of saidfibers being coated with a polymeric composition; andb) a second panel attached to the first panel, which second panel isdifferent than the first panel, and which second panel comprises aplurality of fibrous layers, said plurality of fibrous layers beingconsolidated; each of the fibrous layers comprising a plurality offibers, said fibers having a tenacity of about 7 g/denier or more and atensile modulus of about 150 g/denier or more; each of said fibershaving a surface, and the surfaces of said fibers being coated with apolymeric composition; andc) said first panel containing a greater percentage by weight of thepolymeric composition in the first panel, based on the total weight ofthe first panel, than a percentage by weight of the polymericcomposition in said second panel, based on the total weight of thesecond panel; andd) at least one additional panel attached to the first panel, to thesecond panel, or to both the first panel and to the second panel, the atleast one additional panel comprising a plurality of fibrous layers,said plurality of fibrous layers being consolidated; each of the fibrouslayers comprising a plurality of fibers, said fibers having a tenacityof about 7 g/denier or more and a tensile modulus of about 150 g/denieror more; each of said fibers having a surface, and the surfaces of saidfibers optionally being coated with a polymeric composition.

DETAILED DESCRIPTION

The invention provides a ballistic resistant material and articles thathave superior ballistic penetration resistance against high energyballistic threats, including bullets and high energy fragments, such asshrapnel. The material includes two or more individual attached panels,each panel comprising high strength fibers having a tenacity of about 7g/denier or more and a tensile modulus of about 150 g/denier or more.Most broadly, a ballistic resistant material of the invention comprisesa first panel attached to a second panel, each panel comprising aplurality of fibrous layers, said plurality of fibrous layers beingconsolidated; each of the fibrous layers comprising a plurality offibers, said fibers having a tenacity of about 7 g/denier or more and atensile modulus of about 150 g/denier or more; each of said fibershaving a surface, and the surfaces of said fibers being coated with apolymeric composition. As described herein, the first panel contains agreater percentage by weight of the polymeric composition in the firstpanel, based on the total weight of the first panel, than a percentageby weight of the polymeric composition in said second panel, based onthe total weight of the second panel. As described herein, the totalweight of a panel is the weight of the fibers plus the weight of thepolymeric composition that form the panel. The ballistic resistantmaterial and articles of the invention may further include additionalpanels, preferably forming a series of interconnected ballisticresistant panels, wherein consecutive panels in the series contains alower percentage by weight of the polymeric composition than theprevious panel in the series to which it is connected, based on thetotal weight of each panel, and wherein each panel may comprise wovenfibers or non-woven fibers, or a combination thereof.

For the purposes of the present invention, a “fiber” is an elongate bodythe length dimension of which is much greater than the transversedimensions of width and thickness. The cross-sections of fibers for usein this invention may vary widely.

They may be circular, flat or oblong in cross-section. Accordingly, theterm fiber includes filaments, ribbons, strips and the like havingregular or irregular cross-section. They may also be of irregular orregular multi-lobal cross-section having one or more regular orirregular lobes projecting from the linear or longitudinal axis of thefibers. It is preferred that the fibers are single lobed and have asubstantially circular cross-section.

As used herein, a “yarn” is a strand consisting of multiple filaments.An “array” describes an orderly arrangement of fibers or yarns, and a“parallel array” describes an orderly parallel arrangement of fibers oryarns. A fiber “layer” describes a planar arrangement of woven ornon-woven fibers or yarns. A fiber “network” denotes a plurality ofinterconnected fiber or yarn layers. As used herein, the term“interconnected” describes a reciprocal connection of the multiplelayers or multiple panels of the invention, such that the structurefunctions as a single unit. A “consolidated network” describes aconsolidated (merged) combination of fiber layers with a polymericcomposition. As used herein, a “single layer” structure refers tomonolithic structure composed of one or more individual fiber layersthat have been consolidated into a single unitary structure. In general,a “fabric” may relate to either a woven or non-woven material.

The invention presents various embodiments that include two or moreballistic resistant panels, where each panel may comprise non-wovenfibrous layers, woven fibrous layers, or a combination thereof. In thepreferred embodiments of the invention, a panel of non-woven fibrouslayers preferably comprises a single-layer, consolidated network offibers and an elastomeric or rigid polymeric composition, whichpolymeric composition is also referred to in the art as a polymericmatrix composition. The terms “polymeric composition” and “polymericmatrix composition” are used interchangeably herein. More particularly,a single-layer, consolidated network of fibers comprises a plurality offibrous layers stacked together, each fibrous layer comprising aplurality of fibers coated with the polymeric composition andunidirectionally aligned in an array so that they are substantiallyparallel to each other along a common fiber direction.

As is conventionally known in the art, excellent ballistic resistance isachieved when individual fiber layer are cross-plied such that the fiberalignment direction of one layer is rotated at an angle with respect tothe fiber alignment direction of another layer. Accordingly, successivelayers of such unidirectionally aligned fibers are preferably rotatedwith respect to a previous layer. An example is a two layer (two ply)structure wherein adjacent layers (plies) are aligned in a 0°/90°orientation, where each individual non-woven ply is also known as a“unitape”. However, adjacent layers can be aligned at virtually anyangle between about 0° and about 90° with respect to the longitudinalfiber direction of another layer. For example, a five ply non-wovenstructure may have plies at a 0°/45°/90°/45°/0° orientation or at otherangles. In the preferred embodiment of the invention, only twoindividual non-woven plies, cross-plied at 0° and 90°, are consolidatedinto a single layer network, wherein one or more of said single layernetworks make up a single non-woven panel. However, it should beunderstood that the single-layer consolidated networks of the inventionmay generally include any number of cross-plied (or non-cross-plied)plies. Most typically, the single-layer consolidated networks includefrom 1 to about 6 plies, but may include as many as about 10 to about 20plies as may be desired for various applications. Such rotatedunidirectional alignments are described, for example, in U.S. Pat. Nos.4,457,985; 4,748,064; 4,916,000; 4,403,012; 4,623,573; and 4,737,402.Likewise, a “panel” is a monolithic structure that may include anynumber of component fiber layers or plies, and typically includes 1 toabout 65 fiber layers or plies, and each panel may comprise a pluralityof fibrous layers which comprise non-woven fibers, a plurality offibrous layers which comprise woven fibers, or a combination of wovenfibrous layers and non-woven fibrous layers. A ballistic resistantmaterial of the invention may also comprise at least one panel whichcomprises a plurality of fibrous layers which comprise non-woven fibersand at least one panel which comprises a plurality of fibrous layerswhich comprise woven fibers.

The stacked fibrous layers are consolidated, or united into a monolithicstructure by the application of heat and pressure, to form thesingle-layer, consolidated network, merging the fibers and the polymericcomposition of each component fibrous layer. The non-woven fibernetworks can be constructed using well known methods, such as by themethods described in U.S. Pat. No. 6,642,159. The consolidated networkmay also comprise a plurality of yarns that are coated with such apolymeric composition, formed into a plurality of layers andconsolidated into a fabric. The non-woven fiber networks may alsocomprise a felted structure which is formed using conventionally knowntechniques, comprising fibers in a random orientation embedded in asuitable polymeric composition that are matted and compressed together.

For the purposes of the present invention, the term “coated” is notintended to limit the method by which the polymeric composition isapplied onto the fiber surface or surfaces. The application of thepolymeric composition is conducted prior to consolidating the fiberlayers, and any appropriate method of applying the polymeric compositiononto the fiber surfaces may be utilized. Accordingly, the fibers of theinvention may be coated on, impregnated with, embedded in, or otherwiseapplied with a polymeric composition by applying the composition to thefibers and then optionally consolidating the composition-fiberscombination to form a composite. As stated above, by “consolidating” itis meant that the polymeric composition material and each individualfiber layer are combined into a single unitary layer. Consolidation canoccur via drying, cooling, heating, pressure or a combination thereof.The term “composite” refers to consolidated combinations of fibers withthe polymeric matrix composition. The term “matrix” as used herein iswell known in the art, and is used to represent a polymeric bindermaterial that binds the fibers together after consolidation.

The woven fibrous layers of the invention are also formed usingtechniques that are well known in the art using any fabric weave, suchas plain weave, crowfoot weave, basket weave, satin weave, twill weaveand the like. Plain weave is most common. Prior to weaving, theindividual fibers of each woven fibrous material may or may not becoated with a polymeric composition in a similar fashion as thenon-woven fibrous layers using the same polymeric compositions as thenon-woven fibrous layers.

As described herein, each panel of woven or non-woven fibrous layerspreferably comprises a plurality of fibrous layers, where the greaterthe number of layers translates into greater ballistic resistance, butalso greater weight. A non-woven fibrous panel, in particular,preferably comprises two or more layers that are consolidated into amonolithic panel. A woven fibrous panel may also comprise a plurality ofconsolidated woven fibrous layers, which are consolidated by moldingunder pressure. In a preferred structure of the invention, a first panelwhich comprises ten consolidated layers of a woven fibrous material isattached one surface of a second panel which comprises ten non-wovenfibrous layers consolidated into a single layer network, and a thirdpanel comprising ten consolidated layers of a woven fibrous material isattached to an opposing surface of the second panel.

The number of layers forming a single panel, and the number of layersforming the non-woven composite vary depending upon the ultimate use ofthe desired ballistic resistant article. For example, in body armorvests for military applications, in order to form an article compositethat achieves a desired 1.0 pound per square foot areal density (4.9kg/m²), a total of at 22 individual layers (or plies) may be required,wherein the plies may be woven, knitted, felted or non-woven fabricsformed from the high-strength fibers described herein, and the layersmay or may not be attached together. In another embodiment, body armorvests for law enforcement use may have a number of layers based on theNational Institute of Justice (NIJ) Threat Level. For example, for anNIJ Threat Level IIIA vest, there may also be a total of 22 layers. Fora lower NIJ Threat Level, fewer layers may be employed.

The invention is characterized in particular by combining multiplepanels that contain different quantities of a polymeric composition, asmeasured by the total weight of the fibers plus the polymericcomposition forming the panel. Articles of the invention may include asfew as two panels, wherein each panel comprises a monolithic structure,and wherein each of the two panels includes a different quantity amountof a polymeric composition. More preferably, articles of the inventioninclude three or more monolithic panels, where each panel preferablyincludes a different quantity amount of a polymeric composition. It isfurther within the scope of the invention that each of the multiplemonolithic panels of the invention may be attached by furtherconsolidating (merging, preferably by molding) the panels to formanother monolithic structure, said another monolithic structureincorporating multiple panels having differing amounts of the polymericmatrix composition, and accordingly having different sections which havedifferent amounts of the polymeric matrix composition representing thelocation of each of the different panels.

In each embodiment of the invention, some panels may include identicalquantities of a polymeric matrix composition. However, the totalpolymeric matrix composition content of at least two panels forming anarticle must differ. In an alternate embodiment of the invention, aballistic resistant article comprises at least one ballistic resistantpanel wherein the fibers forming the panel are not coated with apolymeric composition. If present, such an uncoated, polymericmatrix-free panel is preferably part of a series of interconnectedballistic resistant panels wherein at least one panel of the seriesincludes a polymeric composition. Methods of attaching orinterconnecting multiple panels are well known in the art, and includestitching, quilting, bolting, adhering with adhesive materials, and thelike. Multiple panels may also be attached by molding under the moldingconditions herein described. Preferably, said plurality of panelsforming a series are interconnected by stitching together at edge areasof the panels.

In the preferred embodiments of the invention, each panel comprises afiber content of at least about 65% by weight, more preferably at leastabout 70% by weight, more preferably at least about 75%, and mostpreferably at least about 80% by weight of the total weight of thepanel. Preferably, the proportion of the polymeric composition making upeach panel preferably comprises from about 1% to about 35% by weightbased on the total weight of each panel composite, more preferably fromabout 3% to about 30% by weight, more preferably from about 5% to about25% by weight and most preferably from about 7% to about 20% by weightof the panel, based on the total weight of the fibers and polymericcomposition of each panel. These weight ranges apply to panels formedwith the same polymeric composition or different polymeric compositions.Preferably, each panel has the same polymeric composition coating.Examples of preferred embodiments non-exclusively include: 1) atwo-panel article wherein the first panel has a polymeric compositioncontent of approximately 20% by weight of the combined weight of itsfibers and the polymeric composition, and the second panel has apolymeric composition content of approximately 10% by weight of thecombined weight of its fibers and polymeric composition; 2) a series offour interconnected panels, the panels having respective polymericcomposition quantities, in order, of 20%, 15%, 10% and 7%, said panelspreferably being stitched together; and 3) a three-panel article similarto the two-panel article described above, but having a matrix-free thirdpanel attached to the 10% matrix-containing panel.

The woven or non-woven fibrous layers of the invention may be preparedusing a variety of polymeric composition (polymeric matrix composition)materials, including both low modulus, elastomeric materials and highmodulus, rigid materials. Suitable polymeric composition materialsnon-exclusively include low modulus, elastomeric materials having aninitial tensile modulus less than about 6,000 psi (41.3 MPa), and highmodulus, rigid materials having an initial tensile modulus at leastabout 300,000 psi (2068 MPa), each as measured at 37° C. by ASTM D638.As used herein throughout, the term tensile modulus means the modulus ofelasticity as measured by ASTM 2256 for a fiber and by ASTM D638 for apolymeric composition material.

An elastomeric polymeric composition may comprise a variety of polymericand non-polymeric materials. The preferred elastomeric polymericcomposition comprises a low modulus elastomeric material. For thepurposes of this invention, a low modulus elastomeric material has atensile modulus, measured at about 6,000 psi (41.4 MPa) or lessaccording to ASTM D638 testing procedures. Preferably, the tensilemodulus of the elastomer is about 4,000 psi (27.6 MPa) or less, morepreferably about 2400 psi (16.5 MPa) or less, more preferably 1200 psi(8.23 MPa) or less, and most preferably is about 500 psi (3.45 MPa) orless. The glass transition temperature (Tg) of the elastomer ispreferably less than about 0° C., more preferably the less than about−40° C., and most preferably less than about −50° C. The elastomer alsohas a preferred elongation to break of at least about 50%, morepreferably at least about 100% and most preferably has an elongation tobreak of at least about 300%.

A wide variety of materials and formulations having a low modulus may beutilized as the polymeric composition. Representative examples includepolybutadiene, polyisoprene, natural rubber, ethylene-propylenecopolymers, ethylene-propylene-diene terpolymers, polysulfide polymers,polyurethane elastomers, chlorosulfonated polyethylene, polychloroprene,plasticized polyvinylchloride, butadiene acrylonitrile elastomers,poly(isobutylene-co-isoprene), polyacrylates, polyesters, polyethers,fluoroelastomers, silicone elastomers, copolymers of ethylene, andcombinations thereof, and other low modulus polymers and copolymerscurable below the melting point of the polyolefin fiber. Also preferredare blends of different elastomeric materials, or blends of elastomericmaterials with one or more thermoplastics. The polymeric composition mayalso include fillers such as carbon black or silica, may be extendedwith oils, or may be vulcanized by sulfur, peroxide, metal oxide orradiation cure systems as is well known in the art.

Particularly useful are block copolymers of conjugated dienes and vinylaromatic monomers. Butadiene and isoprene are preferred conjugated dieneelastomers. Styrene, vinyl toluene and t-butyl styrene are preferredconjugated aromatic monomers. Block copolymers incorporatingpolyisoprene may be hydrogenated to produce thermoplastic elastomershaving saturated hydrocarbon elastomer segments. The polymers may besimple tri-block copolymers of the type A-B-A, multi-block copolymers ofthe type (AB)_(n) (n=2-10) or radial configuration copolymers of thetype R-(BA)_(x) (x=3-150); wherein A is a block from a polyvinylaromatic monomer and B is a block from a conjugated diene elastomer.Many of these polymers are produced commercially by Kraton Polymers ofHouston, Tex. and described in the bulletin “Kraton ThermoplasticRubber”, SC-68-81. The most preferred polymeric composition polymercomprises styrenic block copolymers sold under the trademark Kraton®commercially produced by Kraton Polymers. The most preferred low moduluspolymeric matrix composition comprises apolystyrene-polyisoprene-polystrene-block copolymer.

Preferred high modulus, rigid polymeric composition materials usefulherein include materials such as a vinyl ester polymer or astyrene-butadiene block copolymer, and also mixtures of polymers such asvinyl ester and diallyl phthalate or phenol formaldehyde and polyvinylbutyral. A particularly preferred rigid polymeric composition materialfor use in this invention is a thermosetting polymer, preferably solublein carbon-carbon saturated solvents such as methyl ethyl ketone, andpossessing a high tensile modulus when cured of at least about 1×10⁶ psi(6895 MPa) as measured by ASTM D638. Particularly preferred rigidpolymeric composition materials are those described in U.S. Pat. No.6,642,159, which is incorporated herein by reference.

In addition to the non-woven fibrous layers, the woven fibrous layersare also preferably coated with the polymeric composition. Preferablythe fibers comprising the woven fibrous layers are at least partiallycoated with a polymeric composition, followed by a consolidation stepsimilar to that conducted with non-woven fibrous layers. However,coating the woven fibrous layers with a polymeric composition is notrequired. For example, a plurality of woven fibrous layers forming apanel of the invention do not necessarily have to be consolidated, andmay be attached by other means, such as with a conventional adhesive, orby stitching. Generally, a polymeric composition coating is necessary toefficiently merge, i.e. consolidate, a plurality of fibrous layers. Inthe preferred embodiment of the invention, a matrix-free panel, ifincluded, preferably comprises one or more woven fibrous layers that arenot coated with a polymeric composition, wherein multiple woven layersmay be joined by stitching or any other common method.

The rigidity, impact and ballistic properties of the articles formedfrom the fabric composites of the invention are affected by the tensilemodulus of the polymeric composition polymer. For example, U.S. Pat. No.4,623,574 discloses that fiber reinforced composites constructed withelastomeric matrices having tensile moduli less than about 6000 psi(41,300 kPa) have superior ballistic properties compared both tocomposites constructed with higher modulus polymers, and also comparedto the same fiber structure without a polymeric matrix composition.However, low tensile modulus polymeric matrix composition polymers alsoyield lower rigidity composites. Further, in certain applications,particularly those where a composite must function in bothanti-ballistic and structural modes, there is needed a superiorcombination of ballistic resistance and rigidity. Accordingly, the mostappropriate type of polymeric composition polymer to be used will varydepending on the type of article to be formed from the fabrics of theinvention. In order to achieve a compromise in both properties, asuitable polymeric composition may combine both low modulus and highmodulus materials to form a single polymeric composition.

The remaining portion of the composite is preferably composed of fibers.In accordance with the invention, the fibers comprising each of thewoven and non-woven fibrous layers preferably comprise high-strength,high tensile modulus fibers. As used herein, a “high-strength, hightensile modulus fiber” is one which has a preferred tenacity of at leastabout 7 g/denier or more, a preferred tensile modulus of at least about150 g/denier or more, and preferably an energy-to-break of at leastabout 8 J/g or more, each both as measured by ASTM D2256. As usedherein, the term “denier” refers to the unit of linear density, equal tothe mass in grams per 9000 meters of fiber or yarn. As used herein, theterm “tenacity” refers to the tensile stress expressed as force (grams)per unit linear density (denier) of an unstressed specimen. The “initialmodulus” of a fiber is the property of a material representative of itsresistance to deformation. The term “tensile modulus” refers to theratio of the change in tenacity, expressed in grams-force per denier(g/d) to the change in strain, expressed as a fraction of the originalfiber length (in/in).

Particularly suitable high-strength, high tensile modulus fibermaterials include polyolefin fibers, particularly extended chainpolyolefin fibers, such as highly oriented, high molecular weightpolyethylene fibers, particularly ultra-high molecular weightpolyethylene fibers and ultra-high molecular weight polypropylenefibers. Also suitable are aramid fibers, particularly para-aramidfibers, polyamide fibers, polyethylene terephthalate fibers,polyethylene naphthalate fibers, extended chain polyvinyl alcoholfibers, extended chain polyacrylonitrile fibers, polybenzazole fibers,such as polybenzoxazole (PBO) and polybenzothiazole (PBT) fibers, andliquid crystal copolyester fibers. Each of these fiber types isconventionally known in the art.

In the case of polyethylene, preferred fibers are extended chainpolyethylenes having molecular weights of at least 500,000, preferablyat least one million and more preferably between two million and fivemillion. Such extended chain polyethylene (ECPE) fibers may be grown insolution spinning processes such as described in U.S. Pat. No. 4,137,394or 4,356,138, which are incorporated herein by reference, or may be spunfrom a solution to form a gel structure, such as described in U.S. Pat.Nos. 4,551,296 and 5,006,390, which are also incorporated herein byreference. A particularly preferred fiber type for use in the inventionare polyethylene fibers sold under the trademark SPECTRA® from HoneywellInternational Inc. SPECTRA® fibers are well known in the art and aredescribed, for example, in U.S. Pat. Nos. 4,623,547 and 4,748,064.

Also particularly preferred are aramid (aromatic polyamide) orpara-aramid fibers. Such are commercially available and are described,for example, in U.S. Pat. No. 3,671,542. For example, usefulpoly(p-phenylene terephthalamide) filaments are produced commercially byDupont corporation under the trade name of KEVLAR®. Also useful in thepractice of this invention are poly(m-phenylene isophthalamide) fibersproduced commercially by Dupont under the trade name NOMEX® and fibersproduced commercially by Teijin under the trade name TWARON®.

Suitable polybenzazole fibers for the practice of this invention arecommercially available and are disclosed for example in U.S. Pat. Nos.5,286,833, 5,296,185, 5,356,584, 5,534,205 and 6,040,050, each of whichare incorporated herein by reference. Preferred polybenzazole fibers areZYLON® brand fibers from Toyobo Co. Suitable liquid crystal copolyesterfibers for the practice of this invention are commercially available andare disclosed, for example, in U.S. Pat. Nos. 3,975,487; 4,118,372 and4,161,470, each of which is incorporated herein by reference.

Suitable polypropylene fibers include highly oriented extended chainpolypropylene (ECPP) fibers as described in U.S. Pat. No. 4,413,110,which is incorporated herein by reference. Suitable polyvinyl alcohol(PV-OH) fibers are described, for example, in U.S. Pat. Nos. 4,440,711and 4,599,267 which are incorporated herein by reference. Suitablepolyacrylonitrile (PAN) fibers are disclosed, for example, in U.S. Pat.No. 4,535,027, which is incorporated herein by reference. Each of thesefiber types is conventionally known and are widely commerciallyavailable.

The other suitable fiber types for use in the present invention includeglass fibers, fibers formed from carbon, fibers formed from basalt orother minerals, rigid rod fibers such as M5® fibers, and combinations ofall the above materials, all of which are commercially available. Forexample, the fibrous layers may be formed from a combination of SPECTRA®fibers and Kevlar® fibers. M5® fibers are manufactured by MagellanSystems International of Richmond, Va. and are described, for example,in U.S. Pat. Nos. 5,674,969, 5,939,553, 5,945,537, and 6,040,478, eachof which is incorporated herein by reference. Specifically preferredfibers include M5® fibers, polyethylene SPECTRA® fibers, and aramidKevlar® fibers. The fibers may be of any suitable denier, such as, forexample, 50 to about 3000 denier, more preferably from about 200 to 3000denier, still more preferably from about 650 to about 2000 denier, andmost preferably from about 800 to about 1500 denier.

The most preferred fibers for the purposes of the invention are eitherhigh-strength, high tensile modulus extended chain polyethylene fibersor high-strength, high tensile modulus para-aramid fibers. As statedabove, a high-strength, high tensile modulus fiber is one which has apreferred tenacity of about 7 g/denier or more, a preferred tensilemodulus of about 150 g/denier or more and a preferred energy-to-break ofabout 8 J/g or more, each as measured by ASTM D2256. In the preferredembodiment of the invention, the tenacity of the fibers should be about15 g/denier or more, preferably about 20 g/denier or more, morepreferably about 25 g/denier or more and most preferably about 30g/denier or more. The fibers of the invention also have a preferredtensile modulus of about 300 g/denier or more, more preferably about 400g/denier or more, more preferably about 500 g/denier or more, morepreferably about 1,000 g/denier or more and most preferably about 1,500g/denier or more. The fibers of the invention also have a preferredenergy-to-break of about 15 J/g or more, more preferably about 25 J/g ormore, more preferably about 30 J/g or more and most preferably have anenergy-to-break of about 40 J/g or more.

These combined high strength properties are obtainable by employing wellknown processes. U.S. Pat. Nos. 4,413,110, 4,440,711, 4,535,027,4,457,985, 4,623,547 4,650,710 and 4,748,064 generally discuss theformation of preferred high strength, extended chain polyethylene fibersemployed in the present invention. Such methods, including solutiongrown or gel fiber processes, are well known in the art. Methods offorming each of the other preferred fiber types, including para-aramidfibers, are also conventionally known in the art, and the fibers arecommercially available.

As discussed above, the polymeric composition (matrix) may be applied toa fiber in a variety of ways, and the term “coated” is not intended tolimit the method by which the polymeric composition is applied onto thefiber surface or surfaces. For example, the polymeric composition may beapplied in solution form by spraying or roll coating a solution of thepolymeric composition onto fiber surfaces, wherein a portion of thesolution comprises the desired polymer or polymers and a portion of thesolution comprises a solvent capable of dissolving the polymer orpolymers, followed by drying. Another method is to apply a neat polymerof the coating material to fibers either as a liquid, a sticky solid orparticles in suspension or as a fluidized bed. Alternatively, thecoating may be applied as a solution or emulsion in a suitable solventwhich does not adversely affect the properties of the fiber at thetemperature of application. For example, the fiber can be transportedthrough a solution of the polymeric composition to substantially coatthe fiber and then dried to form a coated fiber. The resulting coatedfiber can then be arranged into the desired network configuration. Inanother coating technique, a layer of fibers may first be arranged,followed by dipping the layer into a bath of a solution containing thepolymeric composition dissolved in a suitable solvent, such that eachindividual fiber is substantially coated with the polymeric composition,and then dried through evaporation of the solvent. The dipping proceduremay be repeated several times as required to place a desired amount ofpolymeric composition coating on the fibers, preferably encapsulatingeach of the individual fibers or covering 100% of the fiber surface areawith the polymeric composition.

While any liquid capable of dissolving or dispersing a polymer may beused, preferred groups of solvents include water, paraffin oils andaromatic solvents or hydrocarbon solvents, with illustrative specificsolvents including paraffin oil, xylene, toluene, octane, cyclohexane,methyl ethyl ketone (MEK) and acetone. The techniques used to dissolveor disperse the coating polymers in the solvents will be thoseconventionally used for the coating of similar materials on a variety ofsubstrates.

Other techniques for applying the coating to the fibers may be used,including coating of the high modulus precursor (gel fiber) before thefibers are subjected to a high temperature stretching operation, eitherbefore or after removal of the solvent from the fiber (if using thegel-spinning fiber forming technique). The fiber may then be stretchedat elevated temperatures to produce the coated fibers. The gel fiber maybe passed through a solution of the appropriate coating polymer underconditions to attain the desired coating. Crystallization of the highmolecular weight polymer in the gel fiber may or may not have takenplace before the fiber passes into the solution. Alternatively, thefiber may be extruded into a fluidized bed of an appropriate polymericpowder. Furthermore, if a stretching operation or other manipulativeprocess, e.g. solvent exchanging, drying or the like is conducted, thecoating may be applied to a precursor material of the final fiber. Inthe most preferred embodiment of the invention, the fibers of theinvention are first coated with the polymeric composition, followed byarranging a plurality of fibers into either a woven or non-woven fiberlayer. Such techniques are well known in the art.

Each panel described herein has outer surfaces. In a preferredembodiment of the invention, at least one polymer film is attached to atleast one outer surface of at least one panel. A polymer film may bedesired to decrease friction between panels, because some panel typeshave sticky or rubbery surfaces. Suitable polymers for said polymer filmnon-exclusively include thermoplastic and thermosetting polymers.Suitable thermoplastic polymers non-exclusively may be selected from thegroup consisting of polyolefins, polyamides, polyesters, polyurethanes,vinyl polymers, fluoropolymers and co-polymers and mixtures thereof. Ofthese, polyolefin layers are preferred. The preferred polyolefin is apolyethylene. Non-limiting examples of polyethylene films are lowdensity polyethylene (LDPE), linear low density polyethylene (LLDPE),linear medium density polyethylene (LMDPE), linear very-low densitypolyethylene (VLDPE), linear ultra-low density polyethylene (ULDPE),high density polyethylene (HDPE). Of these, the most preferredpolyethylene is LLDPE. Suitable thermosetting polymers non-exclusivelyinclude thermoset allyls, aminos, cyanates, epoxies, phenolics,unsaturated polyesters, bismaleimides, rigid polyurethanes, silicones,vinyl esters and their copolymers and blends, such as those described inU.S. Pat. Nos. 6,846,758, 6,841,492 and 6,642,159. As described herein,a polymer film includes polymer coatings.

Such optional polymer films may be attached to one or both of the outersurfaces of a panel using well known lamination techniques. Typically,laminating is done by positioning the individual layers on one anotherunder conditions of sufficient heat and pressure to cause the layers tocombine into a unitary film. The individual layers are positioned on oneanother, and the combination is then typically passed through the nip ofa pair of heated laminating rollers by techniques well known in the art.Lamination heating may be done at temperatures ranging from about 95° C.to about 175° C., preferably from about 105° C. to about 175° C., atpressures ranging from about 5 psig (0.034 MPa) to about 100 psig (0.69MPa), for from about 5 seconds to about 36 hours, preferably from about30 seconds to about 24 hours. Alternately, a polymeric film may beattached to a panel during a molding step described below. In thepreferred embodiment of the invention, optional polymer film layerswould comprise from about 2% to about 25% by weight based on thecombined weight of the fibers, polymeric composition and polymer films,more preferably from about 2% to about 17% percent by weight and mostpreferably from 2% to 12% by weight. The percent by weight of thepolymer film layers will generally vary depending on the number offabric layers forming a panel.

In forming the panels of the invention, multiple fibrous layers arepreferably molded under heat and pressure in a suitable moldingapparatus. Generally, the panels are molded at a pressure of from about50 psi (344.7 kPa) to about 5000 psi (34470 kPa), more preferably about100 psi (689.5 kPa) to about 1500 psi (10340 kPa), most preferably fromabout 150 psi (1034 kPa) to about 1000 psi (6895 kPa). The fibrouslayers may alternately be molded at higher pressures of from about 500psi (3447 kPa) to about 5000 psi, more preferably from about 750 psi(5171 kPa) to about 5000 psi and more preferably from about 1000 psi toabout 5000 psi. The molding step may take from about 4 seconds to about45 minutes. Preferred molding temperatures range from about 200° F.(˜93° C.) to about 350° F. (˜177° C.), more preferably at a temperaturefrom about 200° F. to about 300° F. (˜149° C.) and most preferably at atemperature from about 200° F. to about 280° F. (˜121° C.). Suitablemolding temperatures, pressures and times will generally vary dependingon the type of polymeric composition type, polymeric compositioncontent, and type of fiber. The pressure under which the fabrics of theinvention are molded has a direct effect on the stiffness or flexibilityof the resulting molded product. Particularly, the higher the pressureat which the fabrics are molded, the higher the stiffness, andvice-versa. In addition to the molding pressure, the quantity, thicknessand composition of the fabric layers, polymeric composition type andoptional polymer film also directly affects the stiffness of thearticles formed from the inventive fabrics.

While each of the molding and consolidation techniques described hereinmay appear similar, each process is different. Particularly, molding isa batch process and consolidation is a continuous process. Further,molding typically involves the use of a mold, such as a shaped mold or amatch-die mold when forming a flat panel.

If a separate consolidation step is conducted to form one or more singlelayer, consolidated networks prior to molding, the consolidation may beconducted in an autoclave, as is conventionally known in the art. Whenheating, it is possible that the polymeric composition can be caused tostick or flow without completely melting. However, generally, if thepolymeric composition material is caused to melt, relatively littlepressure is required to form the composite, while if the polymericcomposition material is only heated to a sticking point, more pressureis typically required. The consolidation step may generally take fromabout 10 seconds to about 24 hours. Similar to molding, suitableconsolidation temperatures, pressures and times are generally dependenton the type of polymer, polymer content, process used and type of fiber.

The panels or fabrics of the invention may optionally be calendaredunder heat and pressure to smooth or polish their surfaces. Calendaringmethods are well known in the art and may be conducted prior to or aftermolding.

The multiple panels of the invention may be adjoined in a bonded arrayor may be juxtaposed in a non-bonded array. Methods of bonding are wellknown in the art, and include stitching, quilting, bolting, adheringwith adhesive materials, and the like. Preferably, said plurality oflayers are attached by stitching together at edge areas of the layers.

The thickness of the individual fabric layers and panels will correspondto the thickness of the individual fibers. Accordingly, a preferredwoven fibrous layer will have a preferred thickness of from about 25 μmto about 500 μm, more preferably from about 75 μm to about 385 μm andmost preferably from about 125 μm to about 255 μm. A preferredsingle-layer, consolidated network will have a preferred thickness offrom about 12 μm to about 500 μm, more preferably from about 75 μm toabout 385 μm and most preferably from about 125 μm to about 255 μm. Apolymer film is preferably very thin, having preferred thicknesses offrom about 1 μm to about 250 μm, more preferably from about 5 μm toabout 25 μm and most preferably from about 5 μm to about 9 μm. Aballistic resistant article, including a series of interconnectedballistic resistant panels and any optional polymer films, has apreferred total thickness of about 5 μm to about 1000 μm, morepreferably from about 6 μm to about 750 μm and most preferably fromabout 7 μm to about 500 μm. While such thicknesses are preferred, it isto be understood that other film thicknesses may be produced to satisfya particular need and yet fall within the scope of the presentinvention. The multi-panel articles of the invention further have apreferred areal density of from about 0.25 lb/ft² (psf) (1.22 kg/m²(ksm)) to about 2.0 psf (9.76 ksm), more preferably from about 0.5 psf(2.44 ksm) to about 1.5 psf (7.32 ksm), more preferably from about 0.7psf (3.41 ksm) to about 1.5 psf (7.32 ksm), and most preferably fromabout 0.75 psf (3.66 ksm) to about 1.25 psf (6.1 ksm).

In another embodiment, at least one rigid plate may be attached to aballistic resistant article of the invention to increase protectionagainst armor piercing projectiles. In ballistic resistant vestapplications, articles including a rigid plate are commonly desirable.Such a rigid plate may comprise a ceramic, a glass, a metal-filledcomposite, a ceramic-filled composite, a glass-filled composite, acermet, high hardness steel (HHS), armor aluminum alloy, titanium or acombination thereof, wherein the rigid plate and the inventive panelsare stacked together in face-to-face relationship. Preferably only onerigid plate is attached to the top surface of a series of panels, ratherthan to each individual panel of a series. The three most preferredtypes of ceramics include aluminum oxide, silicon carbide and boroncarbide.

The ballistic panels of the invention may incorporate a singlemonolithic ceramic plate, or may comprise small tiles or ceramic ballssuspended in flexible resin, such as polyurethane. Suitable resins arewell known in the art. Additionally, multiple layers or rows of tilesmay be attached to the plates of the invention. For example, multiple3″×3″×0.1″ (7.62 cm×7.62 cm×0.254 cm) ceramic tiles may be mounted on a12″×12″ (30.48 cm×30.48 cm) panel using a thin polyurethane adhesivefilm, preferably with all ceramic tiles being lined up with such that nogap is present between tiles. A second row of tiles may then be attachedto the first row of ceramic, with an offset so that joints arescattered. This continues all the way down to cover the entire armor.For high performance at the lowest weight, it is preferred that panelsare molded before attaching a rigid plate. However, for large panels,e.g. 4′×6′ (1.219 m×1.829 m) or 4′×8′ (1.219 m×2.438 m), a panel may bemolded in a single, low pressure autoclave process together with a rigidplate.

The multi-panel structures of the invention may be used in variousapplications to form a variety of different ballistic resistant articlesusing well known techniques. For example, suitable techniques forforming ballistic resistant articles are described in, for example, U.S.Pat. Nos. 4,623,574, 4,650,710, 4,748,064, 5,552,208, 5,587,230,6,642,159, 6,841,492 and 6,846,758.

The multi-panel structures are particularly useful for the formation offlexible, soft armor articles, including garments such as vests, pants,hats, or other articles of clothing, and covers or blankets, used bymilitary personnel to defeat a number of ballistic threats, such as 9 mmfull metal jacket (FMJ) bullets and a variety of fragments generated dueto explosion of hand-grenades, artillery shells, Improvised ExplosiveDevices (IED) and other such devises encountered in military and peacekeeping missions. As used herein, “soft” or “flexible” armor is armorthat does not retain its shape when subjected to a significant amount ofstress and is incapable of being free-standing without collapsing. Themulti-panel structures are also useful for the formation of rigid, hardarmor articles. By “hard” armor is meant an article, such as helmets,panels for military vehicles, or protective shields, which havesufficient mechanical strength so that it maintains structural rigiditywhen subjected to a significant amount of stress and is capable of beingfreestanding without collapsing. The structures can be cut into aplurality of discrete sheets and stacked for formation into an articleor they can be formed into a precursor which is subsequently used toform an article. Such techniques are well known in the art.

Garments of the invention may be formed through methods conventionallyknown in the art. Preferably, a garment may be formed by adjoining theballistic resistant articles of the invention with an article ofclothing. For example, a vest may comprise a generic fabric vest that isadjoined with the ballistic resistant structures of the invention,whereby the inventive articles are inserted into strategically placedpockets. For best soft armor results, the panels having the least amountof polymeric composition should be positioned closest to a potentialballistic threat and the panels having the greatest amount of thepolymeric composition should be positioned furthest from the potentialballistic threat. For best hard armor results, the panels having thegreatest quantity of the polymeric composition should be positionedclosest to a potential ballistic threat, and the panels having the leastamount of polymeric composition should be positioned furthest from apotential ballistic threat. This allows for the maximization ofballistic protection, while minimizing the weight of the vest. As usedherein, the terms “adjoining” or “adjoined” are intended to includeattaching, such as by sewing or adhering and the like, as well asun-attached coupling or juxtaposition with another fabric, such that theballistic resistant articles may optionally be easily removable from thevest or other article of clothing. Articles used in forming flexiblestructures like flexible sheets, vests and other garments are preferablyformed from using a low tensile modulus polymeric matrix composition.Hard articles like helmets and armor are preferably formed using a hightensile modulus polymeric matrix composition.

The ballistic resistance properties are determined using standardtesting procedures that are well known in the art. Particularly, theprotective power or penetration resistance of a structure is normallyexpressed by citing the impacting velocity at which 50% of theprojectiles penetrate the composite while 50% are stopped by the shield,also known as the V₅₀ value. As used herein, the “penetrationresistance” of an article is the resistance to penetration by adesignated threat, such as physical objects including bullets,fragments, shrapnel and the like, and non-physical objects, such as ablast from explosion. For composites of equal areal density, which isthe weight of the composite panel divided by the surface area, thehigher the V₅₀, the better the resistance of the composite. Theballistic resistant properties of the articles of the invention willvary depending on many factors, particularly the type of fibers used tomanufacture the fabrics.

Flexible ballistic armor formed herein preferably have a V₅₀ of at leastabout 1920 feet/second (fps) (585.6 msec) when impacted with a 16 grainprojectile. Flexible ballistic armor formed herein preferably have a V₅₀of at least about 1400 feet/second (fps) (427 m/sec) when impacted witha 17 grain fragment simulated projectile (fsp).

The following non-limiting examples serve to illustrate the invention.

Example 1

Two continuous rolls of unidirectional fiber prepregs (unitapes) wereprepared from SPECTRA® fibers. The unitapes contained 18 wt. % of apolymeric matrix composition consisting of KRATON® D1107styrene-isoprene-styrene block copolymer elastomer. The rolls wereplaced on the cross-plying machine described in U.S. Pat. No. 5,173,138.The prepregs were cross-plied at 0°/90° and consolidated under heat andpressure to create a continuous two-ply structure. The continuous rollwas further laminated between two 0.35 mil (0.0089 mm) thick LLDPE filmsusing heat and pressure, forming a laminated continuous roll (LCR). Thematerial from this roll is designated as Material A in Table 1 (SR-3111SPECTRA® Shield product).

Twenty five two-ply pieces measuring 45.72 cm×45.72 cm were cut from theMaterial A LCR laminates and stacked in an array without molding orotherwise interconnecting the pieces together. The article so formed wassubjected to ballistic testing against a 9 MM Full Metal Jacket (FMJ)bullet (8.04 g weight) according to NIJ Standard 0101.04 Revision A.Results of the ballistic testing are shown in Table 1.

Example 2

In addition to the LCR in Example 1 with 18% polymeric matrixcomposition content, another LCR was manufactured with 11 wt % of apolymeric matrix composition consisting of KRATON® D1107styrene-isoprene-styrene block copolymer elastomer. The material fromthis roll is designated as Material B in Table 1 (SR-3121 SPECTRA®Shield product).

Fourteen two-ply pieces measuring 45.72 cm×45.72 cm were cut fromMaterial B and thirteen two-ply pieces measuring 45.72 cm×45.72 cm werecut from Material A. All twenty seven pieces from Material B andMaterial A were stacked together in a single array without molding orotherwise interconnecting the pieces together. The article so formed wassubjected to ballistic testing against a 9 MM FMJ bullet (124 grain,8.04 g weight) according to NIJ Standard 0101.04 Revision A whereMaterial B faced the bullet. Results of the ballistic testing are shownin Table 1. As listed in the Tables below, Material 1 is the panelpositioned to be struck first by a ballistic threat; Material 2 is thepanel positioned to be struck second by the ballistic threat.

Example 3

Similar to Example 2, fourteen two-ply pieces measuring 45.72 cm×45.72cm were cut from Material A and thirteen two-ply pieces measuring 45.72cm×45.72 cm were cut from Material B. All twenty seven pieces fromMaterial A and Material B were stacked together in a single arraywithout molding or otherwise interconnecting the pieces together. Thearticle so formed was subjected to ballistic testing against a 9 MM FMJbullet (8.04 g weight) according to NIJ Standard 0101.04 Revision A withMaterial A positioned to be struck first by the ballistic threat.Results of the ballistic testing are shown in Table 1.

Example 4

Example 2 was duplicated with another set of two-ply pieces cut fromMaterials B and A (45.72 cm×45.72 cm sample size). Results of theballistic testing are shown in Table 1.

Example 5

Example 3 was duplicated with another set of two-ply pieces cut fromMaterials A and B (45.72 cm×45.72 cm sample size). Results of theballistic testing are shown in Table 1.

Example 6

Twenty-eight two-ply pieces measuring 45.72 cm×45.72 cm were cut fromMaterial B and stacked in an array without molding or otherwiseinterconnecting the pieces together. The article so formed was subjectedto ballistic testing according to NIJ Standard 0101.04 Revision A.Results of the ballistic testing are shown in Table 1. Additional layerswere included compared to Example 1 to account for the difference inmatrix quantity while maintaining the same areal density.

TABLE 1 Total Areal 9 MM Backface Material Material Density FMJ V₅₀Deformation Example 1 2 (kg/m²) (m/sec) (mm) 1 A, 25 two- None 3.76 45036 ply pieces 2 B, 14 two- A, 13 two- 3.76 495 38 ply pieces ply pieces3 A, 14 two- B, 13 two- 3.76 480 39 ply pieces ply pieces 4 B, 14 two-A, 13 two- 3.76 497 40 ply pieces ply pieces 5 A, 14 two- B, 13 two-3.76 487 39 ply pieces ply pieces 6 None B, 28 two- 3.76 495 44 plypieces

The ballistic fragment performance of soft armor summarized in Examples1 to 6 in Table 1 show that:

-   -   1. Varying the quantity of polymeric matrix composition within a        single shoot pack (or flexible vest) increases the ballistic        resistance against a 9 MM FMJ ballistic threat.    -   2. Backface deformation on clay is lower in a shoot pack with        multiple panels having varying polymeric matrix composition        quantities compared to all low resin ballistic material when        tested against a 9 MM FMJ ballistic threat.    -   3. For best soft armor results, the panels having the least        amount of polymeric composition should be positioned closest to        a potential ballistic threat and the panels having the greatest        amount of the polymeric composition should be positioned        furthest from the potential ballistic threat.

Example 7

Two two-ply continuous pre-consolidated rolls (PCRs) were made similarto those shown in Examples 1 and 2, but without adding LLDPE film. Thetwo PCRs have 20% (referred as Material C in Table 2) and 11% (referredas Material D in Table 2) KRATON® D1107 styrene-isoprene-styrene blockcopolymer elastomer as the polymeric matrix composition. As listed inthe Tables below, Material 1 is the panel positioned to be struck firstby a ballistic threat; Material 2 is the panel positioned to be strucksecond by the ballistic threat.

Thirty-seven two-ply pieces measuring 30.48 cm×30.48 cm were cut fromMaterial C, stacked in an array and were molded in a match-die mold,first by pre-heating the stacked pieces for 10 minutes at 120° C.,followed by applying 35 bars molding pressure for 10 minutes, therebyforming a molded panel. Each two-ply piece had a 0°/90° fiberorientation. The molded panel was subjected to ballistic testingaccording to US Military standard MIL-STD-662F, using a .22 caliberfragment simulating projectile weighing 17 grain and followingMIL-P-46593A (ORD). The V₅₀ results of the ballistic testing are shownin Table 2.

Example 8

Twenty two-ply pieces measuring 30.48 cm×30.48 cm were cut from MaterialD and nineteen two-ply pieces were cut from Material C. The two-plypieces of

Material D and Material C were stacked together in a single array andmolded in a match-die mold, first by pre-heating the stacked pieces for10 minutes at 120° C., followed by applying 35 bars molding pressure for10 minutes, thereby forming a molded panel. Each two-ply piece had a0°/90° fiber orientation. The molded panel was subjected to ballistictesting according to US Military standard MIL-STD-662F, using a .22caliber fragment simulating projectile weighing 17 grain and followingMILL-P-46593A (ORD). The V₅₀ results of the ballistic testing are shownin Table 2. The Material D side was facing the incoming fragment duringtesting.

Example 9

Nineteen two-ply pieces measuring 30.48 cm×30.48 cm were cut fromMaterial C and twenty two-ply pieces were cut from Material D. Thetwo-ply pieces of Material C and Material D were stacked together in asingle array and molded in a match-die mold, first by preheating thestacked pieces for 10 minutes at 120 C, followed by applying 35 barsmolding pressure for 10 minutes, thereby forming a molded panel. Eachtwo-ply piece had a 0°/90° fiber orientation. The molded panel wassubjected to ballistic testing according to US Military standardMIL-STD-662F, using a .22 caliber fragment simulating projectileweighing 17 grain and following MILL-P-46593A (ORD). The V₅₀ results ofthe ballistic testing are shown in Table 2. The Material C side wasfacing the incoming fragment during testing.

Example 10

Example 8 was duplicated with another molded panel with another set ofpieces of Material D and Material C. The Material D side was facing theincoming fragment during testing. The V₅₀ results of the ballistictesting are shown in Table 2.

Example 11

Example 9 was duplicated with another molded panel with another set ofpieces of Material C and Material D. Material C side was facing theincoming fragment during testing. The V₅₀ results of the ballistictesting are shown in Table 2, Example 11.

Example 12

Forty-two two-ply pieces measuring 30.48 cm×30.48 cm were cut fromMaterial D, stacked in an array and were molded in a match-die mold,first by preheating the stacked pieces for 10 minutes at 120° C.,followed by applying 35 bars molding pressure for 10 minutes, therebyforming a molded panel. Each two-ply piece had a 0°/90° fiberorientation. The molded panel was subjected to ballistic testingaccording to US Military standard MIL-STD-662F, using a .22 caliberfragment simulating projectile weighing 17 grain and followingMIL-P-46593A (ORD). The V₅₀ results of the ballistic testing are shownin Table 2. Additional layers were included compared to Example 7 toaccount for the difference in matrix quantity while maintaining the sameareal density.

TABLE 2 Material Material Total Areal 17 grain FSP Example 1 2 density(kg/m²) V₅₀ (m/sec) 7 C, 37 two- None 4.97 546 ply pieces 8 D, 20 two-C, 19 two- 4.88 562 ply pieces ply pieces 9 C, 19 two- D, 20 two- 4.97577 ply pieces ply pieces 10 D, 20 two- C, 19 two- 4.93 569 ply piecesply pieces 11 C, 19 two- D, 20 two- 4.97 572 ply pieces ply pieces 12None D, 42 two- 4.97 571 ply pieces

The ballistic fragment performance of hard armor summarized in Examples7 to 12 in Table 2 confirm that by changing polymeric matrix compositioncontent in a single molded panel (made with identical fiber type)increases the ballistic resistance against a .22 caliber, 17 grainfragment simulating projectile. Particularly, Table 2 shows that bypositioning a 20% resin content panel as the front panel of the articlestructure, the ballistic resistance is greater than when it is placed asthe rear panel of the structure. For best hard armor results, the panelshaving the greatest amount of polymeric composition should be positionedclosest to a potential ballistic threat and the panels having the leastamount of the polymeric composition should be positioned furthest fromthe potential ballistic threat.

Example 13

Two continuous pre-consolidated rolls (PCR) were made similar to shownin Example 7. The two PCRs have 20% (referred as Material C in Table 3)and 11% (referred as Material Din Table 3) KRATON® D1107styrene-isoprene-styrene block copolymer elastomer, like Examples 7-12.

One hundred and twenty seven two-ply pieces measuring 30.48 cm×30.48 cmwere cut from Material C, stacked in an array and were molded in amatch-die mold, first by preheating the stacked pieces for 25 minutes at120° C., followed by applying 35 bars molding pressure for 10 minutes,thereby forming a molded panel. Each two-ply piece had a 0°/90° fiberorientation. The molded panel was subjected to ballistic testingaccording to US Military standard MIL-STD-662F, using a high power rifleUS military M80 ball bullet (weight: 9.65 g). Two identical moldedpanels were tested to calculate the V₅₀. The V₅₀ results of theballistic testing are shown in Table 3.

Example 14

Sixty-eight two-ply pieces measuring 30.48 cm×30.48 cm were cut fromMaterial D and sixty-eight two-ply pieces were cut from Material C. Thetwo-ply pieces of Material D and Material C were stacked together in asingle array and molded in a match-die mold, first by preheating thestacked pieces for 25 minutes at 120° C., followed by applying 35 barsmolding pressure for 10 minutes, thereby forming a molded panel. Eachtwo-ply piece had a 0°/90° fiber orientation. The molded panel wassubjected to ballistic testing according to US Military standardMIL-STD-662F, using a high power rifle US military M80 ball bullet(weight: 9.65 g). The Material D side was facing the incoming M80 ballbullet during testing. Two identical molded panels were tested tocalculate the V₅₀. The V₅₀ results of the ballistic testing are shown inTable 3.

Example 15

Sixty-eight two-ply pieces measuring 30.48 cm×30.48 cm were cut fromMaterial C and sixty-eight two-ply pieces were cut from Material D. Thetwo-ply pieces of Material C and Material D were stacked together in asingle array and molded in a match-die mold, first by preheating thestacked pieces for 25 minutes at 120 C, followed by applying 35 barsmolding pressure for 10 minutes, thereby forming a molded panel. Eachtwo-ply piece had a 0°/90° fiber orientation. The molded panel wassubjected to ballistic testing according to US Military standardMIL-STD-662F, using a high power rifle US military M80 ball bullet(weight: 9.65 g). The Material C side was facing the incoming M80 ballbullet during testing. Two identical molded panels were tested tocalculate the V₅₀. The V₅₀ results of the ballistic testing are shown inTable 3.

Example 16

One hundred and forty five two-ply pieces measuring 30.48 cm×30.48 cmwere cut from Material D, stacked in an array and were molded in amatch-die mold, first by preheating the stacked pieces for 25 minutes at120° C., followed by applying 35 bars molding pressure for 10 minutes,thereby forming a molded panel Each two-ply piece had a 0°/90° fiberorientation. The molded panel was subjected to ballistic testingaccording to US Military standard MIL-STD-662F, using a high power rifleUS military M80 ball bullet (147 grain; weight: 9.525 g). Two identicalmolded panels were tested to calculate the V₅₀. The V₅₀ results of theballistic testing are shown in Table 3. Additional layers were includedcompared to Example 13 to account for the difference in matrix quantitywhile maintaining relatively the same areal density.

TABLE 3 Total Areal Material Material density M80 ball Example 1 2(kg/m²) V₅₀ (m/sec) 13 C, 127 two- None 17.03 785 ply pieces 14 D, 68two- C, 68 two- 17.32 797 ply pieces ply pieces 15 C, 68 two- D, 68 two-17.14 844 ply pieces ply pieces 16 None D, 145 two- 17.13 820 ply pieces

The ballistic fragment performance of hard armor summarized in Examples13 to 16 in Table 3 confirm that by changing polymeric matrixcomposition content the resistance against a rifle bullet alsoincreases. For best hard armor results the panels having the greatestamount of polymeric composition should be positioned closest to apotential ballistic threat and the panels having the least amount of thepolymeric composition should be positioned furthest from the potentialballistic threat.

In summary, Examples 1 to 16 show that the ballistic performance of acomposite increases by varying the polymeric matrix composition contentwithin the same ballistic flexible shoot pack or molded panels againstfragments and high energy rifle bullets.

While the present invention has been particularly shown and describedwith reference to preferred embodiments, it will be readily appreciatedby those of ordinary skill in the art that various changes andmodifications may be made without departing from the spirit and scope ofthe invention. It is intended that the claims be interpreted to coverthe disclosed embodiment, those alternatives which have been discussedabove and all equivalents thereto.

What is claimed is:
 1. A ballistic resistant material comprising: afirst panel and a second panel, each comprising a plurality of fibrouslayers, said plurality of fibrous layers being consolidated; each of thefibrous layers comprising a plurality of fibers, said fibers in each ofsaid fibrous layers being the same in each panel and having a tenacityof 7 g/denier or more and a tensile modulus of 150 g/denier or more;each of said fibers having a surface, wherein the surfaces of the fibersof said first panel are coated with a polymeric matrix composition; andwherein the second panel comprises fibers that are not coated with apolymeric matrix composition.
 2. The ballistic resistant material ofclaim 1 wherein both the first panel and the second panel comprise aplurality of non-woven fibrous layers.
 3. The ballistic resistantmaterial of claim 1 wherein the second panel is polymeric matrix-free,wherein the second panel consists of fibers that are not coated with apolymeric matrix composition, and wherein the first panel and the secondpanel are juxtaposed with each other in a non-bonded array.
 4. Theballistic resistant material of claim 1 further comprising at least onerigid plate attached to an outer surface of the first panel, said rigidplate comprising a ceramic, glass, a metal-filled composite, aceramic-filled composite, a glass-filled composite, a cermet, highhardness steel, an armor aluminum alloy, titanium or a combinationthereof.
 5. The ballistic resistant material of claim 1 wherein thefirst panel and the second panel are juxtaposed with each other in anon-bonded array.
 6. The ballistic resistant material of claim 1 whereinthe material consists of the first panel and the second panel, whereinthe first panel and the second panel are juxtaposed with each other in anon-bonded array, and wherein the second panel consists of fibers thatare not coated with a polymeric matrix composition.
 7. A hard armorarticle comprising the ballistic resistant material of claim 1, whereinthe article is a helmet or a vehicle panel.
 8. A ballistic resistantmaterial comprising, in order: a) a first panel comprising a pluralityof fibrous layers, said plurality of fibrous layers being consolidated;each of the fibrous layers comprising a plurality of fibers, said fibershaving a tenacity of 7 g/denier or more and a tensile modulus of 150g/denier or more; each of said fibers having a surface, and the surfacesof said fibers being coated with a polymeric matrix composition; and b)a second panel attached to the first panel, which second panel isdifferent than the first panel, and which second panel comprises aplurality of fibrous layers, said plurality of fibrous layers beingconsolidated; each of the fibrous layers comprising a plurality offibers, said fibers having a tenacity of 7 g/denier or more and atensile modulus of 150 g/denier or more; each of said fibers having asurface, and the surfaces of said fibers being coated with a polymericmatrix composition; and said first panel containing a greater percentageby weight of the polymeric matrix composition in the first panel, basedon the total weight of the first panel, than a percentage by weight ofthe polymeric matrix composition in said second panel, based on thetotal weight of the second panel; and c) one or more additional panelsattached to said second panel, wherein at least one of said additionalpanels comprises fibers that are not coated with a polymeric matrixcomposition; wherein said one or more additional panels comprises aplurality of fibers having a tenacity of 7 g/denier or more and atensile modulus of 150 g/denier or more; wherein said first panel ispositioned closer to a potential ballistic threat relative to the secondpanel.
 9. The ballistic resistant material of claim 8 wherein all of thepanels are interconnected to form a series of interconnected ballisticresistant panels, and wherein each consecutive panel in the seriescontains a lower percentage by weight of the polymeric matrixcomposition than the previous panel in the series to which it isconnected, based on the total weight of each panel, and wherein saidballistic resistant material has an areal density of from about 0.25lb/ft² (1.22 kg/m²) to about 2.0 lb/ft² (9.76 kg/m²).
 10. The ballisticresistant material of claim 8 wherein at least one of said additionalpanels consists of fibers that are not coated with a polymeric matrixcomposition, wherein all of said panels are juxtaposed with each otherin a non-bonded array.
 11. The ballistic resistant material of claim 8comprising a series of three interconnected panels, the panels havingrespective polymeric matrix composition quantities, in order, of 20%,10% and 0% by weight of the combined weight of its fibers and polymericmatrix composition.
 12. The ballistic resistant material of claim 8further comprising at least one rigid plate attached to an outer surfaceof the first panel, said rigid plate comprising a ceramic, glass, ametal-filled composite, a ceramic-filled composite, a glass-filledcomposite, a cermet, high hardness steel, an armor aluminum alloy,titanium or a combination thereof.
 13. The ballistic resistant materialof claim 8 wherein more than one additional panel is present, wherein atleast one of said additional panels comprises fibers that are not coatedwith a polymeric matrix composition.
 14. The ballistic resistantmaterial of claim 13 wherein at least one of said additional panelsconsists of fibers that are not coated with a polymeric matrixcomposition, wherein all of said panels are juxtaposed with each otherin a non-bonded array, and wherein said ballistic resistant material hasan areal density of from about 0.25 lb/ft² (1.22 kg/m²) to about 2.0lb/ft² (9.76 kg/m²).
 15. The ballistic resistant material of claim 13wherein more than one additional panel comprises fibers that are notcoated with a polymeric matrix composition.
 16. The ballistic resistantmaterial of claim 13 wherein more than one additional panel consists offibers that are not coated with a polymeric matrix composition, whereinall of said panels are juxtaposed with each other in a non-bonded array,and wherein said ballistic resistant material has an areal density offrom about 0.25 lb/ft² (1.22 kg/m²) to about 2.0 lb/ft² (9.76 kg/m²).17. The ballistic resistant material of claim 13 further comprising oneor more additional panels attached to said first panel, wherein at leastone of said additional panels comprises fibers that are not coated witha polymeric matrix composition; wherein said one or more additionalpanels comprises a plurality of fibers having a tenacity of 7 g/denieror more and a tensile modulus of 150 g/denier or more, and wherein allof said panels are juxtaposed with each other in a non-bonded array. 18.The ballistic resistant material of claim 17 wherein at least oneadditional panel consisting of fibers that are not coated with apolymeric matrix composition is attached to the first panel and at leastone additional panel consisting of fibers that are not coated with apolymeric matrix composition is attached to the second panel, whereinall of said panels are juxtaposed with each other in a non-bonded array,and wherein said ballistic resistant material has an areal density offrom about 0.25 lb/ft² (1.22 kg/m²) to about 2.0 lb/ft² (9.76 kg/m²).19. A ballistic resistant material comprising: a first panel comprisinga plurality of fibrous layers, said plurality of fibrous layers beingconsolidated; each of the fibrous layers comprising a plurality offibers, said fibers having a tenacity of about 7 g/denier or more and atensile modulus of about 150 g/denier or more; each of said fibershaving a surface, and the surfaces of said fibers being coated with apolymeric composition; and a second panel attached to the first panel,which second panel is different than the first panel, and which secondpanel comprises a plurality of fibrous layers, said plurality of fibrouslayers being consolidated; each of the fibrous layers comprising aplurality of fibers, said fibers having a tenacity of about 7 g/denieror more and a tensile modulus of about 150 g/denier or more; each ofsaid fibers having a surface, and the surfaces of said fibers optionallybeing coated with a polymeric composition; wherein the first panel andthe second panel are juxtaposed with each other in a non-bonded array;and wherein when the surfaces of the fibers of the second panel arecoated with a polymeric composition, said first panel contains a greaterpercentage by weight of the polymeric composition in the first panel,based on the total weight of the first panel, than a percentage byweight of the polymeric composition in said second panel, based on thetotal weight of the second panel.
 20. The ballistic resistant materialof claim 19 wherein both the first panel and the second panel consist ofa plurality of non-woven fibrous layers, wherein the fibers of thesecond panel are coated with a polymeric composition and wherein thepolymeric composition consists of from about 7% to about 20% by weightof the second panel.